By now you may have heard the rumors of a tsunami hitting New Jersey last week and are looking for some more information and confirmation.
As regular visitors to this site know, I work for the National Estuarine Research Reserve System (NERRS), a partner of the National Oceanographic and Atmospheric Administration (NOAA). NERRS and NOAA together operate a wide network of environmental monitoring equipment poised to detect such events. Our data shows that this event did indeed occur, supported by the United States Geological Survey’s ( USGS) tidal monitoring network.
For background information and anecdotal recollection of the tsunami event, I suggest visiting Jay Mann’s Blog. Jay provides feet-on-the-ground and eyes-on reports from LBI in the context of island and coastal living, and his writings provide both informative and entertaining reports from the shore. It turns out that some fishermen were knocked off the Barnegat Inlet jetty by the wave and required rescue, and a number of other ocean- and beach-goers reported a sudden increase in wave action as well.
On June 14th, those in the NERRS network received an email out of the Waquoit Bay reserve in Massachusetts. Their monitoring station closest to the mouth of the estuary detected some very “noisy” data on the 13th, and it was determined the cause was a “meteo-tsunami”, or a tsunami driven by meteorological conditions. While most people associate tsunamis with geological events, meteorological events can “hit the sweet spot” and create a resonating seiche event that manifests as an extremely-long-period wave. Reportedly, the wave in question on the 13th was approximately two feet and resonated within Waquoit Bay for a day or so before its effects settled out and the tidal cycle returned to normal.
So, what caused this phenomenon? Well, you may remember the beast of a thunderstorm system that rolled through our area late in the morning on June 13th , with a wall-cloud approach, derecho winds, and a precipitous drop in barometric pressure (which was captured at the JCNERR’s meteorological station at Nacote Creek/Stockton Marine Field Station).
It appears that when this system ejected off the coast it went extra-tropical and caused enough of a localized pressure differential to create what is called a barotropic wave (when the atmospheric pressure in the middle of a storm decreases, so does the downward force on the surface of the water, which actually causes the water to bulge upwards in the middle of the storm; in some cases, as the storm quickly moves away, this bulge settles back down, displacing a large mass of water, creating a bona fide tsunami, which is what appears to have happened in this event).
Wikipedia provides a good basic description of meteotsunamis here.
Captivated by the quantitative data from Massachusetts as well as qualitative local reports, I was curious if the event was detected by our array of sensors. Unfortunately some of our telemetry stations were knocked offline by Sandy and are awaiting funds to replace them; luckily, the station in the mouth of our estuary, similar to the setup at Waquoit Bay, escaped unscathed and is still transmitting. I was also worried that that its 15-minute interval might have missed the event altogether as these waves can travel quickly and might have impacted the station between sampling windows.
While not as dramatic as the data from our sister reserve, it is obvious that the effects of the tsunami showed up as an aberration in the tidal data at our B6 station on the 13th and reverberated through Great Bay overnight into the next day.
Luckily, the USGS has a tidal sensor situated in the boat basin at the Rutgers University Field Station (RUMFS), within sight of the JCNERR’s B6 station. The data from this sensor concurs with ours.
Finally, data from the scene of the crime, where the fishermen were knocked off the jetty in Barnegat Inlet, has some gaps in the data (I am not sure if the event and the gaps are related- from what I recall the equipment lays pretty low on the platform so it is possible it was vulnerable to the tsunami- but I’ll look into it), it is apparent wave action significantly interfered with the tidal data there in the same manner as the other locations.
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